Quantum mechanical and quasi-classical rate constant calculations for the O(3P)+HCl→OH+Cl reaction

Quantum mechanical (QM) and quasi-classical trajectory (QCT) rate constant calculations for the O(P-3) + HCI(upsilon = 0-2) --> OH + Cl reactions have been carried out on the ab initio potential energy surface (PES) by Koizumi et al. (J. Chem. Phys., 1991, 95, 6421). For the reaction of O(P-3) with HCl(upsilon = 0), the QM cumulative reaction probability for total angular momentum J = 0 was evaluated and the thermal rate constants calculated using the J-shifting approximation. The QM results are in close agreement with those obtained by Thompson and Miller (J. Chem. Phys., 1997, 106, 142; 107, 2164E) and seem to overestimate slightly the experimental determinations. In contrast, the QCT rate constants Clearly underestimate the experimental rate coefficients, indicating that tunneling is important at low collision energies. The QCT rate constant calculations for the reaction with HCl(upsilon = 1, 2) show a. significant enhancement of reactivity with reagent vibrational excitation, in agreement with the experimental observations. For the O(P-3) + HCl(upsilon = 2, j = 1, 6, 9) reactions, the rovibrational populations of the OH product were determined from QCT calculations and a qualitative agreement was found with the existing experimental results and with those obtained previously from QCT calculations on a different ab initio PES.